iron, dopamine, activity, creativity...?

frontiersin |  The present significant associations between iron levels and behavioral and psychological variables extended previous relevant findings reported in infants to adults using a large sample. As described in the Introduction, previous studies of infants with anemia, correlation studies of body iron levels, and intervention studies of iron supplementation have shown that lower body iron or hemoglobin levels are associated with higher levels of negative effects, lower levels of attention to people and objects, and activity levels (Lozoff et al., 1996, 1998, 2003; Wachs et al., 2005). The present findings of the positive associations between novelty seeking, extraversion, and physical activity levels were congruent with these previous results, considering the similarity of extraversion and novelty seeking with the measures reported in the previous study. Thus, it can be said that the present findings extended the previous findings to young adult samples using a larger sample size and suggested that these associations of temperament, personality, body activity levels, and body iron levels are not limited to infants without life experiences.

There are a few limitations to this study. One is that similar to majority of studies using hair mineral analysis, the present study was a cross-sectional study. Thus, despite the strength of the hair mineral analysis and the large study sample, any implications regarding causal effects cannot be viewed as definitive. To solve this problem, intervention studies of iron supplementation are warranted for determining whether iron supplementation can increase dopamine-related traits and physical activity levels. Through these studies, it can be determined whether iron intake can facilitate dopamine-related traits and body activity levels, both of which are essential parts of our social and physical everyday life. In addition, despite the importance of iron in the dopaminergic system, evidence is available that suggests iron accumulation in the brain helps the progression of neurological diseases (Zecca et al., 2004), and whether any detrimental effects of higher iron levels in the body of older subjects are observed, may have to be investigated in future studies. Finally, in this study, the study population was unbalanced toward males due to the low availability of hair that fulfilled these conditions of the study in females, and we did not and could not investigate gender-specific relationships between hair iron levels and psychological variables. The measures used in this study, such as creativity, were measured by DT tests that show gender differences. It is therefore possible that the relationship between iron levels and psychological variables may differ between females and males. Future studies are needed to investigate this issue.

Creative cognition and dopamine-related traits, states, and physical activity levels, which are related to creativity, are important aspects of our cultural and everyday life. Our findings showed that hair iron levels did not significantly and directly correlate with creativity but instead positively correlated with novelty seeking, extraversion, and physical activity levels. Our findings may imply the importance of iron intake, even in normal samples, for the facilitation of these traits and activity. Future longitudinal studies are warranted to confirm these notions.